Activation of the Ga^I Cation for Bond Activation: from Oxidative Additions into C-Cl and H-P Bonds to Reversible Insertion into P₄

Although the discovery of the Ga^I complex salt [Ga(PhF)_2-3 ][Al(OR^F )₄ ] (R^F =C(CF₃ )₃ , PhF=C₆ H₅ F) invoked the preparation of a diverse library of cationic Ga(I) coordination complexes and clusters, studies on small molecule activation with low-valent Ga^I cations are scarce. Herein, a first experimental study on the reactivity of a monomeric Ga(I) cation activated with a pyridine-diimine pincer ligand (in [Ga(PDI^dipp )][Al(OR^F )₄ ]) towards small-molecules is reported. First controlled oxidative additions of the Ga^I cation into C-Cl, H-P and P-P bonds are presented. Moreover, the [4+1]cycloaddition to butadienes was achieved. Intriguingly, the isolated, blue insertion product into the P-P bond of P₄ allows for the quantitative release of the P₄ molecule upon reaction with AlEt₃ and butadienes. Reversible P₄ insertion of main-group metals has previously been reported for Ge and Sn, respectively. The experimental study is supported by high-level computational analysis of the in-part reversible oxidative additions at the DLPNO-CCSD(T)/def2-TZVPP//PBEh-3c/def2-mSVP level of theory with COSMO-RS solvation in 1,2-difluorobenzene.